Harvesting energy from intermittent mechanical disturbances can be of great value for powering remote sensors and other types of electrical circuits such as those supporting wireless transponders. Even if the available disturbances are relatively minor and produce only very small amounts of energy, the sum total of energy collected over time can be enormous benefit for a wide variety of applications. Energy harvesting transducers and energy storage circuitry can effectively provide “self powering circuits” that are far more robust and longer lived than ones powered by a storage battery or can enable hybrid systems with reduced size batteries. These self powered circuits can draw and store energy from mechanical disturbances in the environment around them. This enables them to operate in environments where regular maintenance, to change batteries for example, might be impractical or impossible. The harvested electrical power can be used to provide power for a wide variety of applications such as powering of remote sensors, transmitting telemetry data over a wireless link, local alarm indication, implanted electronic medical devices for therapy or monitoring, and many other uses.
Given the rapid advances in the field of low power circuitry over the last few years, energy harvesting and storage technology is expected to find wide application. Some key requirements for the deployment of these technologies include minimal power consumption, maximum efficiency to optimally harvest and store the power from mechanical disturbances using electromechanical transducers, as well as the need to switch and transform the energy into an optimal form for use by an external application circuit, for example conditioning it to a suitable voltage. Often, the relatively high voltages and currents generated by electromechanical transducers are not readily useable by conventional low power circuitry. Thus, previous energy harvesting technologies suffer from poor efficiencies in collecting, storing and transferring energy from transducers to an application load circuit.